Process for manufacturing fibers and threads from cellulose triacetate



United States Patent 3,081,145 PROCESS FOR MANUFACTURING FIBERS ANDTHREADS FROM CELLULOSE TRIACETATE Paul Ernst and Walter Fischer,Burghausen, Upper Bavaria, Germany, assignors to Celanese Corporation ofAmerica, New York, N.Y., a corporation of Delaware N0 Drawing. FiledMar. 8, 1961, Ser. No. 94,141

. 4 Claims. (Cl. 18-54) This application is a continuation-in-part ofapplication Serial No. 760,532, filed September 12, 1958, the disclosureof which is incorporated herein by reference.

This invention relates to producing fibers and threads from cellulosetriacetate and it has for its object to provide a novel and improvedprocess for this purpose.

Another object of the invention is to provide a simple and efiicientprocess for producing cellulose triacetate fibers and threads havingunusually high tensile strength as well as high extensibility andexcellent transverse elasticity.

It is an object of the invention to permit spinning through a largenumber of orifices without interruption.

Other objects and advantages will become apparent from the followingdetailer description and claims wherein all parts are by weight unlessotherwise specified.

It is known to improve the relatively inferior strength of acetatefibers by stretching the threads or yarns during or after spinning,preferably while in a plastic condition. In this Way resistance totearing may be increased, but at the same time the transverse elasticproperties are impaired. In particular, the stretchability is reduced,and the winding or looping strength becomes diminished.

We have now discovered a process for producing greatly improved fibers,threads and yarns from cellulose triacetate according to the wetspinning process, which have high extensibility, and excellenttransverse elasticity the invention consists substantially in that ahomogeneous solution of cellulose triacetate in a mixture of at. least90% methylene chloride and water-soluble monomeric glycols with 3-6carbon atoms, their polymers and/or univalent alcohols with 1-4 carbonatoms, is spun into a homogeneous precipitation bath which comprises amixture of not more than 70% of said glycols or the mentioned glycolderivatives, etc., as well as their mixtures, particularly semi-ethers,and the remainder of 10-15% methylene chloride as well as water.Suitable as glycols or their semi-ethers or polymers, arepropanediol-l.2, 2-methylpentadiol-2.4, 3 -methylpentanediol-2.4, diandtri-ethyleneglycol, methyland ethylglycol as well as 3-methoxybutanol-l, as well as their mixtures.

It is preferable that the viscosity of the precipitant should not amountto more than 10 cps. and that it have a temperature of 2540 C. The watercontent of said bath can only be so high that the methylene chloride isstill clearly soluble; in this manner optional denier sizes, about l-50den., may be spun.

We have found that as semi-ether, tetrahydrofurfuryl alcohol may beemployed with success in the precipitation bath in the wet spinningtriacetate process. The tetrahydrofurfuryl alcohol employed,

is an interior semi-ether of the 1,4,5 pentanetriol and, under theconditions of our process, results in the pro-.

duction of fibers, threads and yarns having our desired high qualitycharacteristics.

The fibers and threads of cellulose triacetate produced according to ourinvention correspond, with a tensile strength up to 2.5 g., with alltextile requirements as regards superior elongation, cross elasticity,resistance to abrasion, winding strength, etc. the slight regenerativecapacity of the precipitant bath, which need be heated at most to theboiling point of the water in order to recover the methylene chloride.The precipitant adhering to the fibers can be removed by Walsh ing withwater without diificulty and in practice can be quantitativelyrecovered.

In accordance wtih another aspect of the invention it has been foundthat when employing spinnerettes having a large number of orifices aninterruption in spinning occasionally results. This may be overcome bywet spinning into a coagulant comprising about 35 to of a water-solubleglycol or derivative thereof, about 15 to 65% of methylene chloride andthe balance water. Water-soluble glycols and derivatives which areemployed in accordance with the invention include glycols having from 3to 6 carbon atoms, polyglycols, ethers thereof, such as the semi-ethertetrahydrofurfuryl alcohol, or lower alkyl ethers thereof and/or estersthereof with lower fatty acids or inorganic acids.

Spinning is advantageously carried out at a temperature ranging fromabout 5 to 40 C. The viscosity of the coagulant advantageously is nomore than about 10 centipoises and its composition and temperature arechosen accordingly.

To maintain the properties of the coagulant bath unchanged it isnecessary to keep its composition from changing. During spinning amixture rich in solvent is constantly being introduced into thecoagulant thereby enriching the latter with solvent and tending tochange its composition. In order to maintain the coagulant compositionunchanged amixture of glycol or derivative and water is continuouslysupplied'to the coagulant, and simultaneously an appropriate amount ofspent coagulant is withdrawn. Methylene chloride solvent is recoveredfrom the withdrawn spent coagulant by distillation and the glycol-waterresidue is recirculated to the coagulant. The amount of spent coagulantwhich must be withdrawn is quite small as a result of the high methylenechloride content of the equilibrium coagulant and consequently recoveryof methylene chloride is achieved more easily. The best fiber propertiesare achieved by selecting a coagulant composition close to themiscibility limit of the three components which are of limitedmiscibility, viz. glycols or derivatives, water and methylene chloride,since upon further addition of a relatively small amount of water ormethylene chloride the coagulant mixture will separate to form twophases.

By operating in accordance with the invention it is possible to employspinnerettes having more than 2000, e.g. 10,000 or more, orificesWithout interruption of spinning or clogging of the orifices.

The invention is further described in the following illustrativeexamples.

Example 1 A homogeneous mixture of 19 parts by weight of cellulosetriacetate in a mixture of 5 parts by weight of 2- methylpentanediol-2.4and parts by weight of methylene chloride, which has a viscosity ofabout 100,000 cps. at 20 C., is spun through a nozzle With LOGO-2,000apertures each of 0.07 mm. diameter with a speed of 20 m/minute in aprecipitant at 35 C. which consists of 58.5 parts by Weight of2-n1ethylpentanediol-2.4, 31.5 parts by weight of water, 10.0 parts byweight of methyl- A further advantage is one chloride. After the washingthe threads are cut and dried. They have the following properties:

ET den 1.85 Tensile strength g./den 1.91 Elongation percent 31.7Abrasion resistance load 3 Fkm turns 15,000 Winding strength g./den 1.18Winding strength ratio 62% of the tensile strength.

In this and the other examples abrasion resistance load 3 Fkm means thatin the determination of the abrasion resistance the load to be used isto be with a weight of 3 Fkm.

In all the examples all proportions of ingredients are by weight.

Example 2 17.9 parts of cellulose triacetate are dissolved in a mixtureof 90 parts methylene chloride and 10 parts isopropanol. The solution isspun at room temperature and at a drawoif speed of 26 m./minute into aprecipitant which consists of 63% of methoxybutanol-l, 27% water and 10%methylene chloride. The fiber obtained has the following values:

ET den 3.52 Tensile strength g./den 1.76 Elongation percent 34.7Abrasion resistance load 3 Fkm turns 66,500

Winding strength ratio 53% of the tensile strength.

Example 3 ET den 1.17 Tensile strength. g./den 2.40 Elongation percent23.9

Relative winding strength 4.7% of the tensile strength.

Example 4 In a mixture of 95 parts methylene chloride and 5 partsmethanol there are dissolved 17.5 parts cellulose triacetate. Thesolution is spun at 32 C. into a precipitant, at a draw-off speed of 35m./minute, the precipitant consisting of 45% ethyldigylcol, 45% waterand 1.0%

methylene chloride. The fiber obtained has the followingcharacteristics:

ET den 2.32 Tensile strength ..g./den 2.14 Elongation percent 49.3Abrasion resistance load 3 Fkm "turns" 32,000

Winding strength ratio 72% of the tensile strength.

Example 5 A solution of 14.7 parts of triacetate in 95 parts methylenechloride and 5 parts triethylene glycol is spun under the same spinningconditions as described in Example 3 in a precipitation bath consistingof 50 parts Z-methylpentanediol-2,4, 50 parts triethylene glycol, 30parts water and 14.5 parts methylene chloride. of the resultingindividual yarns shows:

ET den 1.84 Tensile strength g./den- 1.84 Elongation percent 34.7

Relative winding strength 65.8% of the tensile strength.

The checking Example 6 A homogeneous solution of 17.4 parts cellulosetriacetate in parts methylene chloride, 5 parts Z-methylpentanediol-2,4and 5 parts methanol is spun in a precipitation 'bath at 32 C.consisting of 25 parts 2methylpentanediol-2,4, 25 parts ethyldiglycol,50 parts water and 7.5 parts methylene chloride. Examination of theindividual yarns shows the following results:

ET den 2.13 Tensile strength g./den 2.03 Elongation percent 37.1Abrasion resistance load 3 Fkrn turns 46,000

Relative winding strength 65% of the tensile strength.

Example 7 A spinning solution composed of 14.7 parts cellulosetriace-tate, 91 parts methylene chloride, 3 partsZ-methylpentanediol-2,4, 3 parts diethylene glycol and 3 parts methanolis spun from a nozzle with 48 holes of 0.07 mm. diameter into a bathconsisting of 54 parts Z-methylpentanediol-2,4, 35 parts water and 15parts methylene chloride. Checking of the individual threads gives:

ET h den 2.46 Tensile strength g./den 2.05 Elongation percent 49.1

Relative winding strength 63% of tensile strength.

Example 8 14.7 parts cellulose triacetate is dissolved in a mixture of90 parts methylene chloride, 5 parts diethylene glycol and 5 partshexanediol-2,5 and spun in a bath composed of 25- parts hexanediol-2,5,75 parts 3-methoxybutanol-1, 40 parts w ater and 15.5 parts methylenechloride. After the usual treatment of washing, drying and cutting thefollowing characteristics are found on checking the individual yarns:

ET den 2.00- Tensile strength g./den 1.80 Elongation percent 44.1

Relative winding strength 74% of tensile strength.

Example 9 A solution of 14.7 parts cellulose triacetate in 95 partsmethylene chloride and 5 parts triethylene glycol is spun in a bathconsisting of 50 parts triethylene glycol, 50 parts 3-methoxybutanol-l,20 parts water and 13.3 parts methylene chloride. Yarns of the followingcharacteristics result:

ET .den 1.93 Tensile strength"; f g./den 1.91 Elongation percent 45.3

Relative winding strength 57% of tensile strength.

Example 10 A solution of 14.7 parts cellulose triacetate in 90 partsmethylene chloride and 10 parts diethylene glycol is spun into aprecipitation bath consisting of 60 parts ethyldiglycol, 40 parts3-methoxybutanol-1, 70 parts water and 18.9 parts methylene chloride.The individual yarn tests reveal the following properties:

ET den 1.79 Tensile strength g./den 2.05 Elongation percent 47.1

Relative winding strength 70% of tensile strength.

Example 11 The spinning solution described in Example 10 is spun into aprecipitation bath composed of 30 parts diethylene glycol, 70 partsmethyldiglycol, 30 parts water and 14.4 parts methylene chloride. Theresulting yarn tests show:

Relative winding strength 69% of tensile strength.

' Example 12 A solution of 17.5 parts tri-acetate in 90 parts methylenechloride and 10 parts methanol is spun from a 48 hole nozzle of 0.07 mm.hole cross-section into a precipitating bath consisting of 45 par-tstetrahydrofurfuryl alcohol, 45 parts water and 10 parts methylenechloride. The drawofi speed is 20 meters per minute. The precipitationbath temperature is 32 C. The washed and dried threads have thefollowing properties:

ET den 2.22 Tensile strength g./den 2.06 Elongation percent- 34.3Abrasion resistance load 3 Fkm revolutions 75,000 Relative windingstrength 68% of tensile strength.

Example 13 Under the conditions described in Example 12 a solutionconsisting of 20 parts cellulose triacetate in 90 parts methylenechloride and 10 parts 2-methylpentanediol-2,4 is spun into aprecipitation bath composed of 40 parts tetrahydrofurfuryl alcohol, 30parts Z-methylpentanedioh 2,4, 30 parts Water and 14 parts methylenechloride. Testing of the fibers gives:

ET den 2.88

Tensile strength g./den 2.31

Elongation percent 33.4

Abrasion resistance load 3 Fkm revolutions 62,000

Relative winding strength 72% of tensile strength.

Example 14 A solution such as described in Example 12 is spun into aprecipitation bath consisting of 50 parts tetrahydrofurfuryl alcohol, 15parts triethylene glycol, 35 parts water and 15 parts methylenechloride. The resulting threads reveal:

ET den 2.06

Tensile strength g./den 1.98

Elongation "percent" 28.3

Abrasion resistance load 3 Fkm revolutions 17,000

Relative winding strength 61% of tensile strength.

Example 15 As in Example 14 there is made a spinning into aprecipitation bath consisting, in this case, of 50 partstetrahydrofurfuryl alcohol, 15 parts 3-methoxybut-anol, 35 parts waterand 15 parts methylene chloride. Characteristics of the threads:

ET den 2.21

Tensile strength g./den 2.04

Elongation percent 24.3

Relative winding strength 67% of tensile strength.

Example 16 The spinning solution of Example 12 is spun into aprecipitation bath consisting of the following mixture: 30 partstetrahydrofurfuryl alcohol, 45 parts. ethyldiglycol, 25 parts water and11 parts methylene chloride. The resulting threads test:

ET den 1.82

Tensile strength g,/den 1.93

Elongation percent 22.9

Relative winding strength 71% of tensile strength.

Example 17 A spinning solution of 1 part of cellulose triacetate, 3.76parts of methylene chloride and 0.24 part by weight of methanol, whichhas a viscosity at 20 C. of 65,000 centipoises, is spun through aspinnerette with 2,000 apertures each of 0.07 mm. diameter into acoagulant made up of 55 parts of 2-methylpentanediol-2,4, 42 parts ofmethylene chloride and 3 parts of water. The temperature of thecoagulant bath is 15 C. and the draw ofi speed of the filaments is 20meters per minute. The filaments are continuously washed by acounter-current stream of water, are cut while still wet, lubricated andthen dried.

The fiber obtained has the following properties:

Denier Tenacity grams per denier 2.11

Elongation percent 16.1

Abrasion reisistance load 3 Fkm turns 12,000

Relative loop tenacity percent 44.5 Example 18 A spinning solution isproduced of 1 part of cellulose triacetate, 4.01 parts of methylenechloride, 0.13 part of methanol and 0.13 part of2-methylpentanediol-2,4, the solution having a viscosity of 37,000centipoises at 20 C. The solution is spun through a ring-shapedspinnerette having 10,032 orifices each of 0.07 mm. diameter into acoagulant at 32 C. consisting of 50 parts of Z-methylpentanediol-2,4, 45parts of methylene chloride and 5 parts of water. The resulting tow istreated as described in Example 17. The fiber obtained has the followingproperties:

Denier 2.16 Tenacity grams per denier 1.87 Elongation percent 23.5

Example 19 Denier 1.92 Tenacity grams per denier 1.83 Elongation percent23.9 Relative loop' tanacity percent 83.1

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of our invention.

Having described our invention What we desire to secure by LettersPatent is:

1. The process which comprises wet spinning cellulose triacetatedissolved in methylene chloride into a co agulant comprising about 35 to75% by weight of a water-soluble member selected (from the groupconsisting of glycols containing about 3 to 6 carbon atoms, polyglycols,ethers thereof and esters thereof, about 15 to 65% by weight ofmethylene chloride and water to proacetate which comprises extruding asolution of cellulose duce cellulose triacetate continuous filamentarymaterial.

2. Process for producing filamentary cellulose tritriacetate in asolvent comprising at least one member selected from the groupconsisting of water-soluble glycols containing from 3 to 6 carbon atoms,poly-lower alkylene glycols and monohydric alcohols containing from 1 to4 carbon atoms and at least about by weight of methylene chloride into ahomogeneous coagulant comprising about 45 to 75 by weight of at leastone member selected from the group consisting of water-soluble 7 glycolscontaining from 3 to 6 carbon atoms, semi-others References Cited n thefile Of this Patent of said poly-lower alkylene glycols, about 10 to 15%UNITED STATES PATENTS f me hylen chlori i nd the h l n o w 2,775,529Bates Dec 25, 1956 3. Process according to claim 2, in which thesemiether is tetrahydrofurfuryl alcohol. 5 FOREIGN PATENTS 4. Processaccording to claim 2, in which the tem- 793,222 Great Britain Apr. 9,1958 796,384 Great Britain June 11, 1958 perature of the precipitationbath tis 20-40" C.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3O81.145 March 12, 1963 Paul Ernst et al.

that error appears in the above numbered pat- It is hereby certifiedthat the said Letters Patent should read as ent requiring correction andcorrected below.

Column 6, line 65, strike out "acetate which comprises extruding as0lut1on of cellulose" and insert the same after "tr1-" 1n line 67, samecolumn 6; column 7, line 7, for "tis" read is Signea; and sealed this28th day of April 1964.

(SEAL) Attest:

ERIiLEST W SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. THE PROCESS WHICH COMPRISES WET SPINNING CELLULOSE TRIACETATEDISSOLVED IN METHYLENE CHLORIDE INTO A COAGULANT COMPRISING ABOUT 35 TO75% BY WEIGHT OF A WATER-SOLUBLE MEMBER SELECTED FROM THE GROUPCONSISTING OF GLYCOLS CONTAINING ABOUT 3 TO 6 CARBONS ATOMS,POLYGLYCOLS, ETHERS THEREOF AND ESTERS THEREOF, ABOUT 15 TO 65% BYWEIGHT OF METHYLENE CHLORIDE AND WATER TO PROACETATE WHICH COMPRISESEXTRUDING A SOLUTION OF CELLULOSE DUE CELLULOSE TRIACETATE CONTINUOUSFILAMENTARY MATERIAL.